It is known as described, for example, in Japanese Patent Application (OPI) NO. 149303/83 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application") that breathable films which are permeable to gases such as water vapor but not to liquids such as water are obtainable by stretching films made of resin compositions comprising a resin, a filler, and so forth. In order to obtain films having high breathability, it is necessary to increase the proportion of the filler in the resin composition or to increase the stretch ratio.
These techniques to increase the breathability, however, decrease film moldability and the strength of formed films and, thus, are limited in their use. Accordingly, films having excellent film moldability and good film strength as well as high breathability cannot be obtained by these techniques. Another technique to increase the breathability wherein films are stretched at low temperatures has a disadvantage in that the resulting breathable films have poor touch and appearance.